Lateral disconnection of foundations: A respectful seismic isolation of historic building

The mitigation of seismic risk for historic buildings faces the critical problem of needing interventions that sometimes can be extremely invasive, thus not respectful of the overall integrity of the valuable structure to protect. Because of this, interventions in the subsoil, possibly without even touching the structure, are appealing, making Geotechnical Seismic Isolation (GSI) of extreme interest for the preservation of the built heritage. The paper shows the results of a centrifuge test carried out to check the simplest possible GSI solution: The lateral disconnection of a shallow foundation, obtained by removing the soil on the sides of the foundation. In this way, the foundation-soil contact will be through the lower base only. The results obtained on two identical structures, one with and one without disconnection, demonstrates that the latter has the beneficial effect of elongating the fundamental period of the soil-structure system in such a way to reduce significantly structural demand. In order to extract additional results, a numerical back analysis of the centrifuge test was also carried out. Since the lateral disconnection does not touch the structure, the integrity of the building to be protected is fully preserved.